JP4530179B2 - Photodiode, ultraviolet sensor including the same, and method for manufacturing photodiode - Google Patents

Description

  The present invention relates to a photodiode that generates light by receiving light including ultraviolet rays, an ultraviolet sensor including the photodiode, and a method for manufacturing the photodiode.

In the conventional ultraviolet sensor, a P-type diffusion layer is formed on each surface layer of two N-type regions formed on a P-type silicon substrate, and an N-type region is formed in a region including an interface between the P-type silicon substrate and each N-type region. An N-type diffusion layer facing the P-type diffusion layer is formed across the mold region, and two vertical PN junction type photodiodes are formed by changing the depth of each P-type diffusion layer. The amount of ultraviolet rays reaching the PN junction under the P-type diffusion layer is changed depending on the depth of the layer, and the light of the photodiode having the deep P-type diffusion layer is changed from the photocurrent of the photodiode having the shallow P-type diffusion layer. An ultraviolet sensor that detects the intensity of light in the ultraviolet region by reducing the current to cancel the photocurrent in the visible light region is formed (see, for example, Patent Document 1).
JP 2007-67331 A (paragraph 0025-paragraph 0035, FIGS. 2 and 3)

  Ultraviolet rays include long wave ultraviolet rays (UV-A wave: wavelength of about 320 to 400 nm), medium wave ultraviolet rays (UV-B wave: wavelength of about 280 to 320 nm), and short wave ultraviolet rays (UV-C wave: wavelength of about 280 nm or less). More than 90% of the ultraviolet rays reaching the ground are composed of UV-A waves, and the rest are UV-B waves, and UV-C waves are not absorbed by the ozone layer and reach the ground. Has been.

In addition, the influence on the human body and the environment differs depending on the wavelength region of ultraviolet rays. In particular, UV-B waves are said to cause inflammation of the skin and induce skin cancer even if the amount of ultraviolet rays reaching the ground is small. Therefore, it is desired to develop an ultraviolet sensor capable of separately detecting UV-B waves.
However, the above-described conventional technique has a problem that although the total amount of ultraviolet rays in the ultraviolet region having a wavelength of 400 nm or less can be detected, the wavelength region cannot be detected separately.

  Further, in the conventional technique described above, the depth of the P-type diffusion layer is changed to change the amount of ultraviolet light of the photocurrent output from the two photodiodes, and the difference between them is calculated to obtain the difference in the ultraviolet region. Since the intensity of light is detected, if the depth of the P-type diffusion layer varies in the step of forming the P-type diffusion layer, the amount of ultraviolet light absorbed by the P-type diffusion layer varies, and the ultraviolet region There is a problem that it is difficult to stabilize the quality of the ultraviolet sensor that detects the intensity of the light.

The present invention has been made to solve the above problems, and an object thereof is to provide means for stably detecting the intensity of light in the ultraviolet region.
It is another object of the present invention to provide means for separately detecting the amount of ultraviolet rays in the wavelength region of the UV-B wave.

  In order to solve the above problems, the present invention has a P-type high-concentration diffusion layer formed in a silicon semiconductor layer in which a P-type impurity is diffused in a high concentration and an N-type impurity is diffused in a high concentration. A lateral PN in which an N-type high-concentration diffusion layer is disposed opposite to the silicon semiconductor layer with a low-concentration diffusion layer formed by diffusing one of P-type and N-type impurities at a low concentration. In the junction type photodiode, an interlayer insulating film is formed on the silicon semiconductor layer, and a covalent bond of silicon and hydrogen is formed in an atomic column adjacent to the interface with the interlayer insulating film of the low concentration diffusion layer It is characterized by that.

  The silicon semiconductor layer on which the low-concentration diffusion layer of the photodiode is formed has a thickness in the range of 3 nm to 36 nm.

  As a result, the present invention allows the thickness of the silicon semiconductor layer when light incident from the interlayer insulating film side passes through a covalent bond (Si-H bond) between silicon and hydrogen formed at the interface with the interlayer insulating film. Regardless of this, UV light in the wavelength region of the UV-A wave can be eliminated by the binding energy, and combined with a photodiode having the same configuration except for the Si-H bond, the UV is calculated by calculation. -To obtain an ultraviolet sensor that can determine the amount of ultraviolet rays only in the wavelength region of the A wave and stably detect the amount of ultraviolet rays in the wavelength region of the UV-A wave that occupies most of the ultraviolet rays that reach the ground. The effect of being able to be obtained.

  Further, since the silicon semiconductor layer on which the low concentration diffusion layer is formed has a thickness in the range of 3 nm or more and 36 nm or less, the ultraviolet energy in the wavelength region of the UV-A wave is cut by the binding energy of the Si-H bond. The transmitted visible light can be cut by the thickness of the silicon semiconductor layer, and a photodiode capable of selectively detecting the amount of ultraviolet light only in the wavelength region of the UV-B wave can be obtained. An effect is obtained.

  Embodiments of a photodiode and a manufacturing method thereof according to the present invention will be described below with reference to the drawings.

1 is an explanatory view showing the upper surface of the photodiode of the embodiment, FIG. 2 is an explanatory view showing the cross section of the photodiode of the embodiment, FIG. 3 is an explanatory view showing the side of the ultraviolet sensor of the embodiment, and FIG. FIG. 5 and FIG. 6 are explanatory views showing a method of manufacturing the photodiode of the embodiment. FIG. 5 and FIG.
2 is a cross-sectional view taken along the line AA in FIG. FIG. 1 shows a state in which a layer above the silicon semiconductor layer shown in FIG. 2 is removed.

In FIG. 1, reference numeral 1 denotes a photodiode, which is a silicon substrate made of thin single crystal silicon with a buried oxide film 3 as an insulating layer made of silicon oxide (SiO ₂ ) sandwiched between a silicon substrate made of silicon (Si) (not shown). This is a lateral PN junction type photodiode formed on the silicon semiconductor layer 4 of the SOI structure semiconductor wafer on which the semiconductor layer 4 is formed.
A diode forming region 6 for forming the photodiode 1 is set on the silicon semiconductor layer 4 of the present embodiment, and an element isolation layer 9 is provided in a region surrounding the diode forming region 6 in a rectangular frame shape. An element isolation region 10 is formed for forming (see FIGS. 5 and 6).

The element isolation layer 9 is formed in the silicon semiconductor layer 4 in the element isolation region 10 in a state of reaching the buried oxide film 3 with an insulating material such as silicon oxide, and the diode formation region 6 is electrically isolated and isolated. It has a function to do.
In this description, as shown in FIG. 1 and the like, the element isolation layer 9 is shaded for distinction.

The photodiode 1 of this embodiment is formed in the diode formation region 6 set in the silicon semiconductor layer 4.
Reference numeral 12 denotes a P + diffusion layer as a P-type high-concentration diffusion layer, which is formed by diffusing P-type impurities such as boron (B) at a relatively high concentration in the silicon semiconductor layer 4 in the diode formation region 6. As shown in FIG. 1, the peak portion 12a in contact with one side inside the element isolation layer 9 and the other side inside the element isolation layer 9 facing the one side from the peak portion 12a. And a plurality of comb teeth 12b extending in a comb shape.

The P + diffusion layer 12 of the present embodiment is formed in a “π” shape by extending two comb teeth portions 12b from the peak portion 12a.
Reference numeral 14 denotes an N + diffusion layer serving as an N-type high-concentration diffusion layer. The silicon semiconductor layer 4 in the diode formation region 6 has a type opposite to that of the P-type high-concentration diffusion layer, that is, phosphorus (P), arsenic (As), or the like. A diffusion layer formed by diffusing an N-type impurity at a relatively high concentration, as shown in FIG. 1, a ridge portion 14 a in contact with the other side inside the element isolation layer 9, and opposed to the ridge portion 14 a It is formed in a comb shape formed with a plurality of comb teeth portions 14b extending toward one side.

The N + diffusion layer 14 of the present embodiment is formed in an “E” shape by extending three comb teeth portions 14b from both ends and the center of the peak portion 14a.
Reference numeral 15 denotes a P− diffusion layer as a low concentration diffusion layer. The P + diffusion layer 12 and the N + diffusion layer 14 which are arranged opposite to each other with the comb-tooth portions 12b and 14b meshed with each other in the diode forming region 6 A diffusion layer formed by diffusing P-type impurities at a relatively low concentration in each of the silicon semiconductor layers 4 that are in contact with each other, and electron-hole pairs are generated by ultraviolet rays absorbed in the depletion layer formed here. It is a part.

  Reference numeral 17 denotes an interlayer insulating film, which is formed on the silicon semiconductor layer 4 and has ultraviolet and visible light in the wavelength region of UV-A waves and UV-B waves such as silicon oxide and NSG (Nondoped Silica Glass), that is, UV- This is an insulating film having a thickness of about 4000 nm made of a transparent insulating material (silicon oxide in this embodiment) that transmits light in a wavelength region of B waves or more.

  Reference numeral 18 denotes a contact hole which is formed in the formation region of the contact plug 19 of the photodiode 1 on the interlayer insulating film 17 and penetrates the interlayer insulating film 17 to reach the P + diffusion layer 12 and the N + diffusion layer 14. The contact plugs 19 are formed by burying a conductive material such as aluminum (Al), tungsten (W), or titanium (Ti) in the contact holes 18.

  Reference numeral 20 denotes a wiring, which is a circuit wiring formed by etching a wiring layer formed of a conductive material similar to that of the contact plug 19 on the interlayer insulating film 17, as shown by a two-dot chain line in FIG. In order not to interfere with the received sunlight, it is arranged so as not to pass over the P− diffusion layer 15 and is electrically connected to the P + diffusion layer 12 and the N + diffusion layer 14 via contact plugs 19 respectively. ing.

Reference numeral 22 denotes a passivation film, which is a protective film having a film thickness of about 300 nm, which is made of silicon nitride (Si ₃ N ₄ ) formed on the interlayer insulating film 17 and transmits light in a wavelength region of UV-B or more. It has a function of protecting the photodiode 1, the wiring 20, and the like from external humidity and the like.
As shown in FIG. 4, silicon (Si) adjacent to the interface 24 of the silicon semiconductor layer 4 is formed at the interface 24 between the P− diffusion layer 15 and the interlayer insulating film 17 formed in the silicon semiconductor layer 4 of this embodiment. The dangling bonds 26 (unbonded hands) of the atomic sequence 25 of the silicon atoms are terminated with hydrogen (H) to form a covalent bond between silicon and hydrogen (referred to as Si—H bond), and the wavelength region of the UV-A wave The filter functions as a filter (referred to as a UV-A filter 27; hatched in FIG. 2) that transmits light in the wavelength range of UV-B waves and below and visible light.

  The bond energy of this Si—H bond is 3.1 to 3.5 eV, which corresponds to energy of a wavelength of about 350 to 400 nm included in the wavelength region of the UV-A wave. When cut by the energy of the A wave, the energy in the wavelength region is absorbed and the ultraviolet light in the wavelength region of the UV-A wave disappears. Therefore, the UV-A formed by the Si—H bond of this embodiment. The filter 27 does not transmit only UV-A waves (see FIG. 7).

In FIG. 3, reference numeral 30 denotes an ultraviolet sensor, and a photo chip 31 a obtained by dividing a semiconductor wafer on which a plurality of photodiodes 1 having the above-described UV-A filter 27 are formed, and a photodiode except for the UV-A filter 27. 1 and a photo chip 31b including a photodiode having the same configuration as that of FIG.
33 is a sealing layer, which is a protective layer formed by heating and curing an ultraviolet transmissive sealing resin that transmits light in the wavelength region of UV-B wave or more, such as silicone resin or epoxy resin, It has a function of protecting the photochips 31a and 31b from external humidity and the like.

As the ultraviolet transmissive sealing resin of the present embodiment, a silicone resin having excellent weather resistance against humidity, ultraviolet rays and the like is used.
The ultraviolet sensor 30 of this embodiment is arranged in parallel with photo chips 31a and 31b on a ceramic substrate 35 on which a plurality of external terminals 34 are formed, and each is joined with silver paste or the like, and exposed to the terminal hole 36 by wire bonding. The wiring 20 and the external terminal 34 are electrically connected by a wire 37 and sealed by a sealing layer 33 made of a silicone resin that covers the photochips 31 a and 31 b on the ceramic substrate 35.

In FIG. 5, reference numeral 40 denotes a resist mask, which is a mask member formed by exposing and developing a positive or negative resist applied on the silicon semiconductor layer 4 by photolithography. It functions as a mask for etching and ion implantation.
The thickness of the silicon semiconductor layer 4 of this example is 40 nm or more and 100 nm or less in order to suppress an increase in sheet resistance of the P + diffusion layer 12 and the N + diffusion layer 14 (in this example, 50 nm). ).

A method for manufacturing the photodiode of this example will be described below in accordance with the process indicated by P in FIGS.
The silicon semiconductor layer 4 of the semiconductor wafer used in this embodiment is an SOI structure semiconductor wafer formed by leaving a thin silicon layer on the buried oxide film 3 by a SIMOX (Separation by Implanted Oxygen) method, or on the buried oxide film 3. A sacrificial oxide film is formed on the thin silicon layer on the buried oxide film 3 of the SOI structure semiconductor wafer formed by sticking a thin silicon layer to the silicon oxide layer by thermal oxidation, and this is removed by wet etching to a thickness of 50 nm. Is formed.

P1 (FIG. 5), the buried oxide film 3 is formed on the element isolation region 10 of the silicon semiconductor layer 4 of the semiconductor wafer on which the 50 nm-thickness silicon semiconductor layer 4 is formed by the LOCOS (Local Oxidation Of Silicon) method. An element isolation layer 9 made of reaching silicon oxide is formed.
Then, P-type impurity ions are implanted at a low concentration into the silicon semiconductor layer 4 in the diode formation region 6 to form a P-type low concentration implantation layer, and the N + diffusion layer 14 formation region in the diode formation region 6 is formed by photolithography. A resist mask 40 (not shown) exposing the (E-shaped portion shown in FIG. 1) is formed, and N-type impurity ions are implanted into the exposed silicon semiconductor layer 4 at a high concentration. A mold high concentration injection layer is formed.

After removing the resist mask 40, a resist mask 40 (not shown) is formed by exposing the P + diffusion layer 12 formation region ("π" -shaped portion shown in FIG. 1) in the diode formation region 6 by photolithography. Then, P-type impurity ions are implanted at a high concentration into the exposed silicon semiconductor layer 4 to form a P-type high concentration implantation layer.
After removing the resist mask 40, the impurities implanted in the respective implantation layers formed in the formation regions of the respective diffusion layers are activated by heat treatment, and a predetermined type of impurity is diffused in each diffusion layer at a predetermined concentration. Then, a P + diffusion layer 12, an N + diffusion layer 14 and a P− diffusion layer 15 are formed in the diode formation region 6, and a plurality of lateral PN junction type photodiodes 1 are formed in the silicon semiconductor layer 4. Prepare the wafer.

P2 (FIG. 5), silicon oxide is deposited on the entire surface of the prepared semiconductor wafer on the silicon semiconductor layer 4 by CVD (Chemical Vapor Deposition), and the upper surface thereof is planarized to form an interlayer insulating film 17 To do.
P3 (FIG. 5), after the formation of the interlayer insulating film 17, the semiconductor wafer is put into a heat treatment apparatus, the temperature of the semiconductor wafer is raised by heat treatment in a hydrogen atmosphere, and P-diffusion formed in the silicon semiconductor layer 4 A dangling bond 26 of the silicon atomic row 25 adjacent to the interface 24 between the layer 15 and the interlayer insulating film 17 is terminated with hydrogen (H) to form a Si—H bond.

In this case, the heat treatment in the hydrogen atmosphere is, for example, a mixed gas atmosphere of 90% nitrogen (N2) and 10% hydrogen (H2) as the gas atmosphere at a temperature in the range of 250 ° C. to 350 ° C. What is necessary is just to heat-process for 30 minutes.
As a result, a UV-A filter 27 that cuts off ultraviolet rays in the wavelength region of the UV-A wave of this embodiment is formed in the region of the P-diffusion layer 15 in contact with the interface 24 with the interlayer insulating film 17.

  After the formation of P4 (FIG. 5) and the UV-A filter 27, the interlayer insulating film in the formation region of the contact hole 18 on the P + diffusion layer 12 and the N + diffusion layer 14 of the photodiode 1 is formed on the interlayer insulating film 17 by photolithography. A resist mask 40 having an opening exposing 17 is formed, and using this as a mask, the P + diffusion layer 12 and the N + diffusion layer 14 penetrate through the interlayer insulating film 17 by anisotropic etching that selectively etches silicon oxide. A contact hole 18 is formed.

  P5 (FIG. 6), the resist mask 40 formed in step P4 is removed, and a contact plug 19 is formed by embedding a conductive material in the contact hole 18 by sputtering or the like. A wiring layer for forming the wiring 20 is formed of the same conductive material, and a resist mask 40 (not shown) that covers the formation region of the wiring 20 is formed on the wiring layer by photolithography, and the wiring layer is formed using this as a mask. The wiring 20 electrically connected to the contact plug 19 is formed by etching, and the resist mask 40 is removed.

P6 (FIG. 6), a passivation film 22 made of silicon nitride is formed on the interlayer insulating film 17 and the wiring 20 on the photodiode 1 by the CVD method.
After that, a resist mask 40 (not shown) having an opening exposing the passivation film 22 in the formation region of the terminal hole 36 on the wiring 20 is formed by photolithography, and the passivation film 22 is etched by anisotropic etching. A terminal hole 36 is formed.

Then, the semiconductor wafer is divided into individual pieces, and a photo chip 31 a including the photodiode 1 on which the UV-A filter 27 is formed is formed.
On the other hand, a plurality of photodiodes formed in a similar manner except for the UV-A filter 27 are formed on a semiconductor wafer in which the silicon semiconductor layer 4 is formed in the same thickness by the process in which the process P3 is omitted, and these are formed into individual pieces. The photo chip 31b in which the UV-A filter 27 is not formed is divided.

  As shown in FIG. 3, these photochips 31a and 31b are arranged in parallel on a ceramic substrate 35, joined with silver paste or the like, respectively, and the wiring 20 exposed in the terminal holes 36 by wire bonding. After electrically connecting the external terminal 34 with the wire 37 and storing it in the mold, a silicone resin is injected by potting, and heated and cured to form a sealing layer 33 that covers the photochips 31a, 31b, etc. Then, the ultraviolet sensor 30 of this embodiment is formed by removing from the mold.

  Since the photo chip 31b includes the photodiode 1 in which the UV-A filter 27 is not formed, the interlayer insulating film 17 that transmits ultraviolet light and visible light in the wavelength region of the UV-A wave and the UV-B wave is transmitted. When light transmitted through the passivation film 22 and the sealing layer 33 made of an ultraviolet transmissive resin is irradiated, the forbidden band width of silicon is about 1.1 eV, and therefore, as shown by a solid line in FIG. It becomes the characteristic which has spectral sensitivity in all the wavelength regions below.

  Further, a photo diode provided with a photodiode 1 having a UV-A filter 27 formed by Si—H bonding at an interface 24 between the P-diffusion layer 15 of the photodiode formed on the photo chip 31 b and the interlayer insulating film 17. When the light incident from the side of the interlayer insulating film 17 passes through the UV-A filter 27 formed at the interface 24 with the interlayer insulating film 17, the chip 31 a uses the binding energy of the Si—H bond for UV-A. Since ultraviolet rays in the wave wavelength region are eliminated, only the UV-A wave can be cut regardless of the thickness of the silicon semiconductor layer, and transmitted through the interlayer insulating film 17 and the like as shown by a broken line in FIG. When the irradiated light is irradiated, the spectral sensitivity of the photochip 31b has a spectral sensitivity in which only ultraviolet rays in the wavelength region of the UV-A wave are cut.

In this case, even if a Si—H bond is formed in another part, for example, the interface between the P− diffusion layer 15 and the buried oxide film 3 in the step P3, the light is irradiated from the interlayer insulating film 17 side. The light after passing through the P− diffusion layer 15 acts on the Si—H bond formed at the interface with the buried oxide film 3, so that the output from the photodiode 1 is not affected.
Thus, except for the UV-A filter 27, the photochip 31a detects from the output in the wavelength region of the UV-A wave, UV-B wave and visible light detected by the photochip 31b having the same configuration. If the output from which only the wavelength region of the UV-A wave is cut is subtracted, the amount of ultraviolet rays in the wavelength region of the UV-A wave can be obtained, and the wavelength of the UV-A wave that occupies most of the ultraviolet rays reaching the ground. The amount of ultraviolet rays in the region can be detected stably.

  Note that the variation in spectral sensitivity of light absorbed by the lateral PN junction type photodiode 1 formed on the photochips 31a and 31b of this embodiment depends on the film thickness of the silicon semiconductor layer 4. When there is a difference due to the variation in the thickness of the silicon semiconductor layer 4 formed on another semiconductor wafer in the spectral sensitivity of the region other than the wavelength region of the UV-A wave, it is visible in the output of the photochip 31b. It is preferable to perform the subtraction after multiplying the magnification that cancels the output of the light region. In this way, it becomes possible to detect the amount of ultraviolet rays more accurately.

  In the present embodiment, the photodiode 1 is described as being formed on the silicon semiconductor layer 4 of the SOI structure semiconductor wafer. However, the photodiode 1 on which the UV-A filter 27 of the present embodiment is formed is an interlayer insulating film. When the light passes through the Si—H bond formed at the interface 24 with the light source 17, the ultraviolet energy in the wavelength region of the UV-A wave is lost by the binding energy. The thickness may be, for example, a bulk substrate made of silicon. In this way, the thickness of the silicon semiconductor layer 4 can be increased to further reduce the variation in spectral sensitivity due to the thickness, and the UV-A filter 27 formed of a bulk substrate is formed. When combined with a non-photodiode, an ultraviolet sensor similar to the above can be obtained.

  Furthermore, in the present embodiment, the P− diffusion layer 15 is described as being formed in the silicon semiconductor layer 4 having the same thickness as the P + diffusion layer 12 and the N + diffusion layer 14, but as shown in FIG. The thickness of the silicon semiconductor layer 4 forming the layer 15 may be the thin silicon semiconductor layer 4 having a thickness in the range of 3 nm to 36 nm (for example, 35 nm) proposed by the applicant in Japanese Patent Application No. 2007-311080. Good.

  In this way, the P-diffusion layer 15 formed in the thin silicon semiconductor layer 4 does not react to light in a wavelength region of visible light or more (wavelength of 400 nm or more), and is incident from the interlayer insulating film 17 side. When the light passes through the UV-A filter 27 formed at the interface 24 with the interlayer insulating film 17, UV light in the wavelength region of the UV-A wave is cut and transmitted by the binding energy of the Si-H bond. Since visible light is cut by the thickness of the silicon semiconductor layer 4, as shown in FIG. 9, it is possible to form a photodiode 1 that can detect only the amount of ultraviolet light in the wavelength region of the UV-B wave alone. It becomes possible.

  In this case, the thin silicon semiconductor layer 4 forming the P − diffusion layer 15 of the photodiode 1 is formed in the diode formation region 6 with the “π” -shaped P + diffusion layer 12 shown in FIG. A thinned region is set as a region for forming the P− diffusion layer 15 sandwiched between the N + diffusion layer 14 and after the heat treatment for forming each diffusion layer in the step P1, the silicon semiconductor layer is formed. A resist mask 40 (not shown) in which the silicon semiconductor layer 4 in the thinned region is exposed is formed on the entire surface of the silicon substrate 4 by photolithography, and the exposed silicon semiconductor layer is formed by anisotropic etching using the resist mask 40 as a mask. 4 is etched to reduce the thickness of the silicon semiconductor layer 4 in the thinned region to the thickness (35 nm) of the silicon semiconductor layer 4 set in the thinned region 7.

If the thin P-diffusion layer 15 is formed in this way and then the processes after the process P2 are performed, the photodiode 1 shown in FIG. 8 can be formed.
As described above, in this embodiment, the interlayer insulating film of the P− diffusion layer of the photodiode in which the P + diffusion layer and the N + diffusion layer formed in the silicon semiconductor layer are opposed to each other with the P− diffusion layer interposed therebetween. By forming a UV-A filter formed of Si-H bonds in an atomic row adjacent to the interface with the light, incident light from the interlayer insulating film side is formed at the interface with the interlayer insulating film. Irrespective of the thickness of the silicon semiconductor layer when passing through the Si-H bond, UV light in the wavelength region of the UV-A wave can be eliminated by the bond energy, and the same except for the UV-A filter. By combining with the configured photodiode, it is possible to calculate the amount of ultraviolet rays only in the wavelength region of the UV-A wave by calculation, and in the wavelength region of the UV-A wave that occupies most of the ultraviolet rays reaching the ground. ultraviolet Amounts can be obtained an ultraviolet sensor which can be stably detected.

  Further, the thickness of the silicon semiconductor layer 4 forming the P-diffusion layer 15 of the photodiode 1 is set to a thickness in the range of 3 nm or more and 36 nm or less, so that the wavelength of the UV-A wave with the binding energy of the Si-H bond. Photodiode capable of selectively detecting the amount of ultraviolet light only in the wavelength region of the UV-B wave by cutting the ultraviolet light in the region and cutting the transmitted visible light depending on the thickness of the silicon semiconductor layer. Can be obtained.

In the above-described embodiment, the two photodiodes of the ultraviolet sensor have been described as being arranged in parallel on the ceramic substrate. However, it is not necessary to arrange them in parallel, as long as they are arranged on the ceramic substrate. .
In the above embodiments, the low-concentration diffusion layer has been described as being formed by diffusing P-type impurities. However, even if an N-type impurity is formed by diffusing at a relatively low concentration, the same as described above. An effect can be obtained.

Further, in the above embodiment, the P + diffusion layer is described as “π” -shaped, and the N + diffusion layer is described as “E” -shaped. However, the respective shapes may be reversed, and the number of comb-tooth portions may be changed. You may increase more.
Further, in the above-described embodiment, the P + diffusion layer and the N + diffusion layer are described as being provided with a plurality of comb teeth portions and meshed with each other. However, only the peak portions are reduced without providing the comb teeth portions. You may make it arrange | position opposingly on both sides of a density | concentration diffusion layer.

  Further, in the above embodiment, the semiconductor wafer is described as being an SOI structure semiconductor wafer having a silicon semiconductor layer formed with a buried oxide film as an insulating layer sandwiched between silicon substrates, or a semiconductor wafer made of a bulk substrate. However, the semiconductor wafer is not limited to the above, and a semiconductor wafer having an SOS (silicon on sapphire) structure in which a silicon semiconductor layer is formed on a sapphire substrate as an insulating layer, or a silicon semiconductor layer is formed on a quartz substrate as an insulating layer. It may be a semiconductor wafer having a SOQ (Silicon On Quartz) structure.

Explanatory drawing which shows the upper surface of the photodiode of an Example Explanatory drawing which shows the cross section of the photodiode of an Example Explanatory drawing which shows the side surface of the ultraviolet sensor of an Example Explanatory drawing which shows the arrangement | sequence of the silicon atom of the interface vicinity of the silicon-semiconductor layer of the photodiode of an Example, and an interlayer insulation film Explanatory drawing which shows the manufacturing method of the photodiode of an Example. Explanatory drawing which shows the manufacturing method of the photodiode of an Example. The graph which shows the spectral sensitivity of two photochips of an Example Explanatory drawing which shows the cross section of the photodiode of the other aspect of an Example. Graph showing the spectral sensitivity of the photodiode of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photodiode 3 Embedded oxide film 4 Silicon semiconductor layer 6 Diode formation area 9 Element isolation layer 10 Element isolation area 12 P + diffusion layer 12a, 14a Peak part 12b, 14b Comb tooth part 14 N + diffusion layer 15 P- diffusion layer 17 Interlayer insulation Film 18 Contact hole 19 Contact plug 20 Wiring 22 Passivation film 24 Interface 25 Atomic array 26 Dangling bond 27 UV-A filter 30 UV sensor 31a, 31b Photo chip 33 Sealing layer 34 External terminal 35 Ceramic substrate 36 Terminal hole 37 Wire 40 Resist mask

Claims (5)

The silicon semiconductor includes a P-type high concentration diffusion layer formed by diffusing P-type impurities in a high concentration and an N-type high concentration diffusion layer formed by diffusing N-type impurities in a high concentration. In a lateral PN junction type photodiode in which a low-concentration diffusion layer formed by diffusing one of P-type and N-type impurities in a low concentration is sandwiched between layers,
An interlayer insulating film is formed on the silicon semiconductor layer, and a covalent bond of silicon and hydrogen is formed in an atomic column adjacent to the interface with the interlayer insulating film of the low-concentration diffusion layer. diode. In claim 1,
The silicon semiconductor layer in which the low concentration diffusion layer is formed has a thickness in the range of 3 nm to 36 nm. The silicon semiconductor includes a P-type high concentration diffusion layer formed by diffusing P-type impurities in a high concentration and an N-type high concentration diffusion layer formed by diffusing N-type impurities in a high concentration. In the layer, two photodiodes of a lateral PN junction type arranged so as to face each other with a low-concentration diffusion layer formed by diffusing either one of P-type and N-type impurities at a low concentration,
An interlayer insulating film is formed on the silicon semiconductor layer of each photodiode, and silicon and hydrogen are shared in an atomic column adjacent to the interface with the interlayer insulating film of the low concentration diffusion layer of one of the photodiodes. An ultraviolet sensor characterized by forming a bond. The silicon semiconductor includes a P-type high concentration diffusion layer formed by diffusing P-type impurities in a high concentration and an N-type high concentration diffusion layer formed by diffusing N-type impurities in a high concentration. A semiconductor wafer is prepared in which a lateral PN junction type photodiode is disposed in which a low-concentration diffusion layer formed by diffusing one of P-type and N-type impurities at a low concentration is sandwiched between layers. And a process of
Forming an interlayer insulating film on the silicon semiconductor layer;
Forming a covalent bond between silicon and hydrogen in an atomic column adjacent to the interface between the low-concentration diffusion layer and the interlayer insulating film by heat treatment in a hydrogen atmosphere. Production method. In claim 4,
The method for manufacturing a photodiode, wherein the silicon semiconductor layer on which the low concentration diffusion layer is formed has a thickness in a range of 3 nm to 36 nm.

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